Kinematic analysis of isokinetic knee flexor and extensor tests

Alt, Tobias; Severin, Jannik; Nodler, Yannick T.; Horn, Dennis; El-Edrissi, Omar; Knicker, Axel; Strüder, Heiko K.

doi:10.3233/ies-175172

Cited by 12 publications

(10 citation statements)

References 16 publications

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“…In line with previous findings, knee flexion angles at peak moment Hecc remained unaffected 27 . Due to the distinctive angular velocity profile during eccentric isokinetic knee flexor movements, knee flexion angles at peak power Hecc remained unchanged as well 17,18 …”

Section: Discussionsupporting

confidence: 91%

“…A double shin pad was attached to the motor‐driven axis. In a pre‐activated muscular state (~50% of maximal effort) at 90° knee flexion, the dynamometer axis was aligned with the participants' lateral femoral epicondyle by use of a laser pointer 17,18 . The pad's distal part was fixed by a strap 2‐3 cm proximal to the medial malleolus.…”

Section: Methodsmentioning

confidence: 99%

“…For knee flexion (110‐0° ROM knee ), participants laid prone by pushing their trunk with the hands to the lounger (Figure 1B). Knee extensions (0‐90° ROM knee ) were performed in supine position with handgrips providing sufficient stability 18 …”

Section: Methodsmentioning

confidence: 99%

“…A custom‐made software (C++) isolated the isokinetic ROM (±1% deviation of angular velocity) and filtered the data (recursive 5th order Butterworth low‐pass filter, 6 Hz cutoff frequency). Camera‐based knee and hip angles were determined three‐dimensionally and sagittal plane kinematics were extracted 17,18 . For each testing condition, the trial with the highest gravity‐corrected peak moment was used for statistical analyses.…”

Section: Methodsmentioning

confidence: 99%

“…Usually, the effect of NHE training on split times have been investigated 5‐7,9,13 . NHE‐induced adaptations of isokinetic outcome parameters relied on dynamometer‐based data 6 which include considerable discrepancies to camera‐based analyses 17,18 . Additionally, low compliance 19 and high athletes' performance level 5,7 diminished NHE‐related effects.…”

Section: Introductionmentioning

confidence: 99%

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Nordic Hamstring Exercise training induces improved lower‐limb swing phase mechanics and sustained strength preservation in sprinters

Alt

Severin

Komnik

et al. 2021

Scandinavian Med Sci Sports

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Nordic Hamstring Exercise (NHE) training improves eccentric hamstring strength and sprint performance. However, detraining causes rapid reductions of achieved adaptations. Furthermore, the transfer of improved hamstring capacity to swing phase mechanics of sprints is unknown. This longitudinal study aimed (a) to quantify NHE‐induced adaptations by camera‐based isokinetic assessments and sprint analyses, (b) to relate the magnitude of adaptations to the participants' initial performance level, (c) to investigate the transferability to sprints, and (4) to determine strength preservations after 3 months. Twelve sprinters (21 years, 1.81 m, 74 kg) were analyzed throughout 22 weeks. They performed maximal sprints and eccentric knee flexor and concentric knee extensor tests before and after a 4‐week NHE training. Sprints and isokinetic tests were captured by ten and four high‐speed cameras. The dynamic control ratio at the equilibrium point (DCRe) evaluated thigh muscle balance. High‐intensity NHE training elicited significant improvements of hamstring function (P range: <.001‐.011, d range: 0.44‐1.14), thigh muscle balance (P < 0.001, d range: 0.80‐1.08) and hamstring‐related parameters of swing phase mechanics (P range: <0.001‐0.022, d range: 0.12‐0.57). Sprint velocity demonstrated small increases (+1.4%, P < 0.001, d = 0.26). Adaptations of hamstring function and thigh muscle balance revealed moderate to strong transfers to improved sprint mechanics (P range: <0.001‐0.048, R2 range: 34%‐83%). The weakest participants demonstrated the highest adaptations of isokinetic parameters (P range: 0.003‐0.023, R2 range: 42%‐62%), whereas sprint mechanics showed no effect of initial performance level. Three months after the intervention, hamstring function (+6% to +14%) and thigh muscle balance (+8% to +10%) remained significantly enhanced (P < 0.001, ƞp2 range: 0.529‐0.621). High‐intensity NHE training induced sustained improved hamstring function of sprinters, which can be transferred to swing phase mechanics of maximal sprints. The initial performance level, NHE training procedures and periodization should be considered to optimize adaptations.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%